Flexible joint couplings have previously been used to connect conduit sections, for example in exhaust pipes or underground water conduits. Such flexible couplings are particularly useful because they allow relative movement between adjacent conduit sections, which permits the conduit sections to flex without breaking. Various flexible couplings have previously been designed that allow pivotal, rotational or axial movement between independent sections of the conduit.
A specific example of a flexible coupling member is shown in U.S. Pat. No. 677,809, wherein the coupling includes two axially spaced steam or liquid conduits. The ends of the conduit, which are to be joined in the coupling, terminate in a ball-shaped end. Each ball shaped end is pivotally held in a hollow case within which the balls can move, which allows the conduits to flex at the case and move relative to one another. The conduits abut against the walls of the case to limit the angular flexion of the conduits.
U.S. Pat. No. 4,776,617 discloses a telescopic swivel pipe joint for flexibly coupling pipes, such as underground water supply lines. This joint allows the connected water lines to slide telescopically within a sleeve, or move pivotally and rotationally inside a separate joint connector. The freedom of movement imparted by the joint helps the pipes withstand earthquakes and ground subsidence without breaking.
Flexible pipe joints have previously been used in engine exhaust systems for gasoline powered vehicles and aircraft. Flexible couplings are important in such an environment, where engine action creates torque that is transmitted to an attached exhaust line. Flexible couplings have been widely used in the past in an attempt to isolate the transmission of this torque through the exhaust conduit to the chassis or muffler.
An example of a flexible conduit joint in an exhaust system is shown in U.S. Pat. No. 2,451,252, wherein the joint includes axially spaced conduit sections joined by flexible ball slip joints. The ball slip joints have wide separations through which gas in the exhaust system leaks from the joints. To avoid this leakage, the separations at each joint are filled with a resilient seal that minimizes loss of exhaust gases from the joint. A flexible bellows also encloses the joint to hermetically seal the conduit against loss of exhaust gases.
U.S. Pat. No. 4,856,822 discloses a series of part-spherical flexible joints for connecting exhaust pipes or other conduits. Each joint includes a pair of part spherical mated sealing surfaces that slide against each other to allow the pipe to pivot.
Additional examples of flexible connectors in exhaust systems are shown in U.S. Pat. No. 5,069,487, U.S. Pat. No. 5,286,071 and U.S. Pat. No. 5,340,165. Each of these patents discloses a bellows sealed ball joint that permits pivotal movement between axially spaced sections of conduit joined by the connector.
Another example of an exhaust line connector is the flexible connector available from Exhaust & Filtration Systems of Stoughton, Wisconsin. The flexible joint of this connector includes a series of interlocking rings. The interlocking rings, however, tend to deform and become locked in place during use. These mechanical problems limit the useful life of the exhaust connector, which typically begins leaking well before the end of the useful life of the vehicle in which the connector is installed.
It is an object of this invention to provide an improved flexible coupling that minimizes the loss of gases (such as exhaust fumes) from the coupling.
Yet another object of the invention is to provide such a coupling that has an extended useful life, and will last (for example) in a vehicle exhaust system for as long as the useful life of the vehicle in which the coupling is used.
Moreover, it is an object of the invention to provide such a coupling that does not require the use of an external bellows or other sealing member to inhibit or prevent the loss of gas from the coupling.